The first time we see Dejah Thoris in combat. A bunch of Zodangan soldiers charge her, and John steps in front of her to protect the obviously Distressed Damsel ("Just get behind me; this could get dangerous"), at which point Dejah whips out a sword and kills three of the soldiers in a matter of seconds.
John Carter: "Maybe I should just get behind you."
Dejah Thoris: "Let me know when it starts getting dangerous."
His entire decade-longBatman Gambit to find not only a way back to Mars but also a Secret Keeper (who turns out to be Edgar Rice Burroughs) to ensure that his body is in safe hands when he does return. All while evading the Therns tracking him down across Earth.
The best part? Edgar has opened the tomb, a Thern is about to strike, and then - BANG! John makes his return in a truly awesome way.
Sola pulls Sarkoja into the arena with her after she says something about Tars Tarkas, and the White Ape tears Sarkoja in two.
The film ends with the title John Carter turning into John Carter of Mars, and the JCM logo finally showing up. May be a Take That against the execs who dropped Mars from the title, to avoid being associated with Mars Needs Moms and/or because they thought girls wouldn't watch a movie with Mars in the title.
Also noticeable as Carter tells Woola "John Carter of Mars sounds way better."
Most people didn't like the very first trailer (and indeed, bad advertising is cited as one of the reasons the movie failed at the box office), but the moment we first see John jump on Mars is incredible.